Improvement in purifying the waste gases from copper-roasting furnaces



UNITED! STATES PATENT OFFICE.

ARTEMAs RIeELoWAND JAMEs y s. BALDWIN, 0F NEWARK, NEW JERSEY, AssIeNoRsTo HENRY MARTIN, 0F BALTIMORE, MARYLAND.

IMPROVEMENT IN PURIFYING THE WASTE GASES FROM COPPER-ROASTING FURNACES.

Specification forming part of Letters Patent N0. 90,067, dated May l,1869.

To all whom t'tmay concern:

Be it known that we, ARTEMAs BIeELow and JAMES S. BALDWIN, of the cityof Newark, in the county of Essex and Stateof New Jersey, have inventeda new and useful Method of Purifying the Waste Gases of Copper-Roastingand Galcining Furnaces for the manufac- 'cined consist of the ordinaryproducts of combustion of the fuel employed, sul urous acid, and theimpurities which it is t e object of our invention to remove. consistot' particles of unconwsumed fuel, empyreumatic substances, ashes, Snc.,and if allowed to enter the chambers where the sulphurous acid isconverted into sulphuric, the latter would be discolored and otherwisecontaminated, and its commercial value seriously impaired. Theseimpurities, which are held in mechanical suspension by the gases alreadymentioned, are removed either' by reducing the current of gas to a stateof partial or total quiescence, or by washing it with Water during itspassage from the furnace to the acid-chambers. 'We prefer to employ theformer method4 in most cases.

The natural draft of the chimneys may, if necessary, be assisted bysteam-jets and revolving fans applied in the usual Way.

In the drawing, Figure I shows the means 4 by which the gases arereduced to a state of partial quiescence, whereby the impurities areallowed to settle down.

It is well known that the velocity of a current is inversely as the areaof the eross-se0 tion of the channel through which it flows. The channelA, into which the gases oW after leaving the furnace, is therefore madesomewhat larger than the outlet ofthe latter, and at B it is ,st-illlfurther enlarged and the speed of the current correspondingly reduced.From B the gases pass to the chamber D through the tubes G C, Thedimensions of D v are such that the flow of the current through it isreduced to an extremely low velocity. From D the gases flow through thechannel E to a second or any additional number of chambers havingequivalent functions. After These impurities their mechanical impuritiesare thus removed,

the gases pass to the chambers, Where the sulphu-rous acid is 'utilizedin the ordinary way.

When it is desired to bring successive portionsof the current to a stateof absolute rest,

the channel is enlarged and divided into two parts, C and D, Fig. II,which are alternately placed in communication with the main chan nel A Bby turning the damper E.

The floors of the several channels described are, if necessary, coveredwith a thin stratum of water to retain the impurities as they settle.

channel is in no case contracted below the dimensions of thc outlet ofthe furnace.

In washing the gases, water is showered through any convenient portionof the channel by a force-pump and rose-jet, or equivalent perforatedoutlet. The water should be used ov'er and over to avoid loss from theabsorption of sulphurous acid. In some cases, however, the current ofgas is so directed, by

screens, tubes, or other suitable deectors,

that it shall impinge upon or pass slightly below the surface of astratum of water, Which will retain the impurities by mechanicaladhesion.

Fig. III represents a simple method of accomplishing this result.

'A B is a portion of a oor, which in practice would occupy the positionG H in' the chamber D, Fig. I. This door sustains a stratum of water,whose upper surface is indi-` cated by the heavy line.

The current of gas is directed by the curved tubes, which, if the draftis sufficiently strong, may dip slightly below the surface of the Water.This arrangement may be repeated any desired number of times in D or insubsequent chambers.

What We claim as our Invention, and desire to secure by Letters Patent,is- Removing the impurities held in mechanical suspension by thewastegases of copper roasting or calcining furnaces by washingl saidgases or reducingthe speed of their flow, by the means substantially asdescribed.

ARTEMAS BIGELOW. JAMES S. BALDWIN.

l, Witnesses:

G. SANDFORD, O. It. SMITH.

That the draft may not be impaired, the'

